1. Field of the Invention
The present invention relates to an output device for providing information by scanning an output medium, and more particularly to an output device capable of providing a line segment connecting specified coordinate points on a record medium.
2. Description of the Prior Art
It is frequently desired to provide character information and graphic information on a single record paper. The graphic information includes normal graphic patterns as well as pattern information of predetermined form such as frame lines, ruled lines or trademarks. In such a case, it has been proposed to print character information on a record paper having a predetermined graphic pattern form printed thereon. With this method, however, when a number of graphic patterns forms are included, a number of different record papers which conform to those forms must be prepared. As a result, the number of types of record paper to be stocked increases and the record paper has to be replaced each time a different form is used.
It has been also proposed to define form information in an output of a computer as a series of special characters, in addition to character information and record the character information and the graphic information on one record paper. The graphic information is processed separately so that the defined form information is sequentially recorded. By regarding the graphic information as form information having a series of special characters, the hardware required for implementing this method need not be large or complex. The cost of such hardware is relatively low and the data transfer time is short. However, in order for any type of graphic patterns to be regarded as form information, software of large volume is required and the computers which can be used for that purpose are necessarily restricted.
A pattern processing system in which a graphic pattern is regarded as a combination of line segments and in which vector data is processed by specifying start points and end points of the line segments is briefly explained below.
A plotter or an X-Y recorder is well known as a graphic output device. However, spot movement in forward and backward directions on an X-axis and a Y-axis, which is employed in the plotter or X-Y recorder, cannot be utilized in a raster scan type recording apparatus. In the raster scan type apparatus, the following method is usually employed. A memory having a sufficiently large memory capacity (approximately 6 M-bits) to store dot information for one page of size A4 record paper is prepared. A processor processes start point and end point information of the vector data, and positions of the line segments connecting the start points and the end points, represented in the form of dots, are written in the memory of the recording apparatus. All vector data are processed in this manner and written in the memory. Subsequently, the data are sequentially read from the memory and recorded on the record paper or other record medium. This system requires a memory having capacity which is large enough to store one page of information at a time. Accordingly, the memory must be of large size, which leads to an increase of cost. When different graphic information, e.g. form information is to be alternately outputted, another memory for storing graphic information data is additionally required. Consequently, the cost of the memories further increases.